Change simulation errors report to an error API, rather than the application log

[adamkewley]

Estimate: 0.5d (incl. updating UI with appropriate error forwarding)

Related: #623

At the moment, the ForwardDynamicSimulator will just return "error" and write the message to the log. This is probably good enough, but a better solution would be to have the error reported to a specialized error API that the UI can hook into (e.g. so that when a user scrolls over the ERROR UI element they can see the error, rather than having to know that the error is actually in the log)

[adamkewley]

Dropping from next release - a few new bugfix tickets (e.g. #645, #644) pushed time out of the schedule and I need to drop ~6 days of development time from the milestone.